Recently, home wastewater treatment systems have become increasingly popular. Prior to the development of home wastewater treatment systems, septic tanks were the conventional manner of cleaning home and small commercial establishment wastes from the water. In view of the great cost associated with connecting a home sewage system with the city sewage system, it is economically beneficial to employ the use of home wastewater treatment systems. Present home wastewater treatment systems are a down-sized, underground version of the treatment processes employed by large central treatment plants.
Essentially, the treatment process correlates with an example found in nature. When a creek runs through rocks and over logs, turbulence is created and oxygen is captured. Aerobic bacteria utilize oxygen in their digestion processes. This allows the creek to purify itself. The home wastewater treatment systems simply employ a speeded-up version of this process in a manner known as "extended aeration". Air or oxygen is brought in by means of an efficient air pump and then diffused into thousands of tiny air bubbles by means of fine air diffusion. As these tiny bubbles move upward through the wastewater, oxygen is captured and the same purification process takes place. Such a system can allow normal household waste water to be reduced to a clear odorless liquid.
One such system has been manufactured and sold by Hydro-Action, Inc. of P.O. Box 12583, Beaumont, Tex. The system is known as the HYDRO-ACTION.TM. system. It is a self-contained automatic system. The HYDRO-ACTION.TM. system incorporates two separate compartments, each performing a specific function in the digestion process. First, raw waste water enters the aeration compartment and is mixed with activated sludge and aerated. An airpump injects large quantities of air into this compartment by means of porous ceramic diffusers located above the bottom perimeter of the aeration compartment. These diffusers create thousands of tiny air bubbles which provide oxygen for the aerobic digestion process and mixes the compartment's entire contents. These tiny bubbles provide better air-to-liquid contact so as to hasten the aerobic digestion process. Aerobic bacteria then use the oxygen in solution to break down the wastewater so as to convert the wastewater into an odorless liquid and gas. Hydraulic displacement causes the mixture to enter the second and final compartment. Due to the calm conditions and sloping walls of the clarification compartment, any remaining settleable material is encouraged to return to the aeration compartment for further treatment. The remaining effluent, upon reaching the outlet piping, is clear and odorless.
This HYDRO-ACTION.TM. system allows homes to be built on clay soil, rock or high water tables. This system also helps to protect the ground water supplies and eliminates gross pollution of ditches and streams. The effluent discharged from such a system is allowed by some state and local regulatory agencies to be discharged directly to a stream or pond or used to surface irrigate lawns and pastures. In areas where surface discharge is not allowed, subsurface disposal methods can be used with good success.
The aforedescribed HYDRO-ACTION.TM. system has been proven to be extremely successful in the treatment of waste. This HYDRO-ACTION.TM. system is the subject of U.S. Pat. No. 5,266,239, issued on Nov. 30, 1993 and entitled "Diffuser Assembly for an Aeration System of a Wastewater Treatment Plant".
Although the HYDRO-ACTION.TM. system has been extremely successful in actual use, there are several improvements which were desired in such a system. First, it was important to improve the accessibility to the aerators within the aeration compartment. In this system, it was necessary to remove the access cover and to reach through openings in the clarifier compartment so as to manipulate and pull the aerator assemblies through the access opening. Since the access opening provided a direct view only to the interior of the clarifier compartment, it was often quite difficult to obtain samples of wastewater within the aeration compartment. Such sampling could only occur after a rather difficult manipulation of instruments threaded through the various components of the system. As such, a need developed so as to allow the aeration conduits and diffusers to be more easily accessible from the top of the buried tank.
Under certain circumstances, it would be necessary to bury the HYDRO-ACTION.TM. system to such a depth that access to the components on the interior of the tank through the access opening was virtually impossible. When the tank would be buried a sufficient depth, it was necessary to attach a series of riser sections in stacked relationship upon the access opening. When a sufficient number of risers were stacked on the access opening, entry into the interior of the tank became even more difficult. Under such circumstances, it was often difficult or impossible to actually install the tank beyond certain depths. Furthermore, in the HYDRO-ACTION.TM. system, when a diffuser assembly became clogged or inoperable, it was necessary to remove the entire aerator assembly so as to properly replace the diffuser. As a result, a need developed so as to allow the system to continue to operate properly even though a single diffuser became clogged or otherwise inoperative.
In the past, various patents have issued relating to such extended aeration wastewater treatment systems. In each of these prior patents, the access opening is located centrally of the top of the tank. The aerator assemblies are arranged peripherally around the clarifier compartment. Each of the conduits extending to the diffusers was fixedly mounted on the interior of each of the tanks. For example, U.S. Pat. No. 4,650,577, issued on Mar. 17, 1987 to B. L. Hansel, describes an apparatus for treating and purifying wastewater. This system includes a vertical tank for receiving wastewater and discharging treated water. A vertical inverted frustoconical clarifying structure is located within the tank and connected to the tank. This clarifier has side walls which diverge from a bottom opening to a larger top opening. A series of air injecting pipes are connected to the tank and located inside the tank for injecting air into the lower portion of the tank to aerate the wastewater in the tank. The aeration pipes are arranged to extend vertically around the exterior of the clarifier compartment. An access opening is provided in the center of the top of the tank so as to allow access to the interior of the tank. Access to the aeration assemblies is extremely difficult through such an access opening. Furthermore, this access opening is located in a position such that sampling of the wastewater in the aeration compartment is difficult or impossible.
U.S. Pat. No. 4,983,285, issued on Jan. 8, 1991, to H. E. Nolen teaches a wastewater treatment plant having an inverted frustoconical-shaped clarifier concentrically suspended within an outer tank. The aeration piping is force fitted into U-shaped slots formed in the support grid for the clarifier. An access opening is provided centrally on the top of the tank. Once again, access to the aeration assemblies becomes very difficult through such a small centrally-located access opening.
U.S. Pat. No. 5,221,470, issued on Jun. 22, 1993 to J. L. McKinney, teaches a wastewater treatment plant that uses aerobic bacteria to digest solid particles in the wastewater. The tank has an inverted frustoconical-shaped clarifier compartment located within the tank. The area between the exterior of the clarifier compartment and the inner surface of the tank wall serves as the aeration chamber. Access to the aerator assemblies is accomplished by fitting a flexible tube through a section of rigid conduit. A diffuser is attached to the end of the flexible tube. A central access opening is provided on the top of the tank. This access opening is positioned directly above the clarifier compartment. This makes the sampling of wastewater in the aeration tank difficult or impossible. Furthermore, the complicated arrangement of rigid conduits and flexible piping makes removal of the diffuser assembly and the associated aerator assembly very difficult. A great deal of manipulation is required so as to remove such diffusers for repair or replacement.
It is an object of the present invention to provide a wastewater treatment system which allows for easy access to the aerator assemblies.
It is another object of the present invention to provide a wastewater treatment system which allows the tank to be installed deeply into the earth while maintaining access to the aerator assembly.
It is another object of the present invention to provide a wastewater treatment system which allows access to the interior of the clarifier compartment and the interior of the aeration chamber so as to facilitate sampling of liquids in such compartments.
It is a further object of the present invention to provide a wastewater treatment system which utilizes a minimal number of aerator assemblies.
It is still a further object of the present invention to provide a wastewater treatment system which reduces the requirements for the replacement of diffusers.
It is still a further object of the present invention to provide a wastewater treatment system which optimizes mixing within the aeration chamber.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.